1/* 2 * include/asm-microblaze/delay.h 3 * 4 * This file is subject to the terms and conditions of the GNU General Public 5 * License. See the file "COPYING" in the main directory of this archive 6 * for more details. 7 * 8 * Copyright (C) 2008 Michal Simek 9 * Copyright (C) 2007 John Williams 10 * Copyright (C) 2006 Atmark Techno, Inc. 11 */ 12 13#ifndef _ASM_MICROBLAZE_DELAY_H 14#define _ASM_MICROBLAZE_DELAY_H 15 16extern inline void __delay(unsigned long loops) 17{ 18 asm volatile ("# __delay \n\t" \ 19 "1: addi %0, %0, -1\t\n" \ 20 "bneid %0, 1b \t\n" \ 21 "nop \t\n" 22 : "=r" (loops) 23 : "0" (loops)); 24} 25 26/* 27 * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so 28 * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32. 29 * 30 * The mul instruction gives us loops = (a * b) / 2^32. 31 * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226 32 * because this lets us support a wide range of HZ and 33 * loops_per_jiffy values without either a or b overflowing 2^32. 34 * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and 35 * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280 36 * (which corresponds to ~3800 bogomips at HZ = 100). 37 * -- paulus 38 */ 39#define __MAX_UDELAY (226050910UL/HZ) /* maximum udelay argument */ 40#define __MAX_NDELAY (4294967295UL/HZ) /* maximum ndelay argument */ 41 42extern unsigned long loops_per_jiffy; 43 44extern inline void __udelay(unsigned int x) 45{ 46 47 unsigned long long tmp = 48 (unsigned long long)x * (unsigned long long)loops_per_jiffy \ 49 * 226LL; 50 unsigned loops = tmp >> 32; 51 52/* 53 __asm__("mulxuu %0,%1,%2" : "=r" (loops) : 54 "r" (x), "r" (loops_per_jiffy * 226)); 55*/ 56 __delay(loops); 57} 58 59extern void __bad_udelay(void); /* deliberately undefined */ 60extern void __bad_ndelay(void); /* deliberately undefined */ 61 62#define udelay(n) (__builtin_constant_p(n) ? \ 63 ((n) > __MAX_UDELAY ? __bad_udelay() : __udelay((n) * (19 * HZ))) : \ 64 __udelay((n) * (19 * HZ))) 65 66#define ndelay(n) (__builtin_constant_p(n) ? \ 67 ((n) > __MAX_NDELAY ? __bad_ndelay() : __udelay((n) * HZ)) : \ 68 __udelay((n) * HZ)) 69 70#define muldiv(a, b, c) (((a)*(b))/(c)) 71 72#endif /* _ASM_MICROBLAZE_DELAY_H */ 73